Cardiac Manifestations of Myotonic Dystrophy in a Pediatric Cohort

Area of Science:

• Cardiology
• Neurology
• Genetics

Background:

• Myotonic dystrophy type 1 (DM1) is a prevalent inherited neuromuscular disorder with multisystemic effects, notably cardiac manifestations.
• Cardiac involvement in pediatric DM1, particularly congenital DM1 (cDM1), is under-researched compared to adults, necessitating further investigation.
• Understanding cardiac disease progression in pediatric DM1 is vital for timely intervention and improved patient outcomes.

Purpose of the Study:

• To investigate the prevalence and progression of cardiac disease in pediatric patients with myotonic dystrophy type 1 (DM1).
• To focus specifically on congenital DM1 (cDM1) and its associated cardiac manifestations and long-term evolution.
• To evaluate the yield of standard cardiac assessments, including ECG and Holter monitoring, in this population.

Main Methods:

• A retrospective observational study included 67 pediatric DM1 patients (56 cDM1, 11 non-cDM1) from December 2000 to November 2020.
• Patients underwent clinical evaluation, 12-lead ECG, transthoracic echocardiography, and 24-h ECG Holter monitoring.
• Cardiac assessments were analyzed at baseline and follow-up to track disease progression over a median follow-up of 8.0 years for cDM1 patients.

Main Results:

• 87.8% of cDM1 patients exhibited ECG abnormalities, most commonly asymptomatic conduction disease (46.9%), including first-degree atrioventricular block (42.9%).
• Progressive ECG changes were observed, with increased prevalence of low QRS voltage, poor R wave progression, abnormal repolarization, and first-degree AVB at follow-up.
• One patient required pacemaker implantation; four cDM1 patients died during follow-up, three from unexplained sudden death, and no patients developed left ventricular systolic dysfunction.

Conclusions:

• This study highlights a high prevalence of ECG abnormalities and progressive cardiac changes in pediatric cDM1 patients.
• The findings underscore the critical need for systematic and ongoing cardiac evaluation in pediatric DM1, including cDM1.
• The observed events, including pacemaker implantation and sudden deaths, emphasize the importance of vigilant cardiac monitoring in this vulnerable population.